FIELD OF THE INVENTION
The present invention relates, to an aluminum alloy powder for sliding members and an aluminum alloy therefor which exhibit such high strength and wear resistance that they are applicable to sliding members of machines such as engines and oil pumps, and at the same time which exhibit extremely low aggressiveness against mating parts, particularly against the mating parts made from aluminum alloys, during sliding operation therewith.
When aluminum alloys and steels are slid or aluminum alloys are slid against each other, the aluminum alloys have been known that they are more likely to be seized than steels. On the other hand, in order to reduce the weight of the engines and the oil pumps, their component parts are often made from the aluminum alloys. Accordingly, there arises the engineering desire to slide the component parts made from the aluminum alloys against each other.
However, as mentioned earlier, the aluminum alloys are seized and worn with ease even under low loads. Consequently, even if the component parts are made from the aluminum alloys and put into practical applications, they are applied to sliding operation under extremely low loads, or either of them is subjected to surface treatment such as plating and thermal spraying.
In order to solve the aforementioned problems of the aluminum alloys, in Japanese Unexamined Patent Publication (KOKAI) No. 55-24,949, Japanese Unexamined Patent Publication (KOKAI) No. 55-97,447, Japanese Unexamined Patent Publication (KOKAI) No. 59-59,855 and Japanese Unexamined Patent Publication (KOKAI) No. 2-70,036, there are proposed to add a solid lubricant, such as graphite, molybdenum disulfide and lead, to an aluminum alloy, and to sinter the mixture, thereby improving the sliding property of the resulting aluminum alloys.
Moreover, in Japanese Unexamined Patent Publication (KOKAI) No. 1-56,844, Japanese Unexamined Patent Publication (KOKAI) No. 2-129,338, Japanese Unexamined Patent Publication (KOKAI) No. 2-194,135 and Japanese Unexamined Patent Publication (KOKAI) No. 3-264,636, there are proposed to add ceramic particles, such as alumina, silicon carbide, zirconium dioxide, aluminum composite oxide and aluminum nitride, and to sinter the mixture, thereby improving the sliding property of the resulting aluminum alloy-based composite materials.
However, the engineering attempts set forth in the publications cannot fully improve the sliding property and wear resistance of the resulting aluminum alloys and aluminum alloy-based composite materials, and accordingly a further improvement has been longed for. In addition, these attempts may sometimes degrade the mechanical strength and machinability of the aluminum alloys and the like.